The present invention relates to vaporized fuel treatment apparatuses that are mainly adapted to be mounted on vehicles.
One example of known vaporized fuel treatment apparatuses will be described. FIG. 31 shows a cross sectional view of one of the vaporized fuel treatment apparatus.
As shown in FIG. 31, a vaporized fuel treatment apparatus 201 has a molded adsorbent 202 with a honeycomb structure capable of adsorbing and desorbing vapor contained in a fuel evaporation gas, a case 203 for housing the molded adsorbent 202, and a pair of holding members 204 and 205 for elastically holding the molded adsorbent 202 in the case 203. The holding member 204 disposed on a front side (right side in FIG. 31) of the molded adsorbent 202 with respect to an insertion direction of the molded adsorbent 202 is formed in a ring shape and includes a circumference surface holding portion 204a engaging with an outer circumference surface of the molded adsorbent 202, and an end surface holding portion 204b engaging with an end surface of the molded adsorbent 202. On the other hand, the holding member 205 disposed on the other side (left side in FIG. 31) of the molded adsorbent 202 with respect to the insertion direction is formed in a ring shape for engaging with the outer circumference surface of the molded adsorbent 202. In addition, a filter 206 made of a non-woven cloth is disposed to oppose to the second surface of the molded adsorbent 202 (left surface in FIG. 31) in order to entirely cover the second surface. This type of vaporized fuel treatment apparatus is disclosed, for example, in Japanese Laid-Open Patent Publication No. 2004-100691 (see paragraph [0082] and FIG. 17).
The molded adsorbent 202 generally has a low mechanical intensity, and especially a shoulder portion 202a formed between the outer circumference surface and the first end surface with respect to an axial direction (the insertion direction) (hereinafter simply referred to as “front end surface”) is weak and fragile. Therefore, when the holding member 204 having the circumference surface 204a contacting with the outer circumference surface of the molded adsorbent 202 and the end surface holding portion 204b contacting with the end surface of the molded adsorbent 202 is used, there has been a problem that the shoulder portion 202a of the molded adsorbent 202 may be damaged during the mounting operation of the holding member 204 on the molded adsorbent 202.
U.S. Pat. No. 5,861,050 discloses a vaporized fuel treatment apparatus including a canister filled with an adsorbent capable of adsorbing vapor generated in a fuel tank. A latent heat storage material is disposed with the canister for inhibiting change in temperature within the canister.
In this vaporized fuel treatment apparatus, the latent heat storage material utilizes latent heat that may be generated during solidification or melting for inhibiting change in temperature and is contained within a sealed container housed within the canister.
When the latent heat storage material absorbs heat and melts, the volume of the latent heat storage material generally increases, and thus a mechanism for compensating the volume increase of the latent heat storage material may be required. However, such a mechanism for compensating the volume increase of the latent heat storage material is not disclosed in U.S. Pat. No. 5,861,050.